OBJECTIVE:To
evaluate the psychometric properties of the Oral Heath Impact Profile (OHIP-14)
to measure oral health in children.METHODS:
The OHIP-14 questionnaire was applied to 312 schoolchildren aged 12 years
residing in Sabará, Brazil, in 2001. OHIP-14's reliability was evaluated
using Cronbach's alpha and correlation intraclass coefficient. For examining
content validity, Pearson's correlation and logistic regression analysis were
applied. For construct validity, Student's t-test and Tukey-Kramer test were
used.RESULTS:
Tooth loss among the subjects was low in this study (between 85% and 100%).
Caries prevalence was very low and not detectable in 59.0% of the sample. The
logistic regression model showed high predictive values for reporting treatment
need and intermediate values for dental caries perception. The comparison between
different OHIP average scores, according to the DMF-S index's three categories
of decayed, missing, filled surfaces, indicated significant difference only
for the categories social disability and deficit.CONCLUSIONS:
The study results indicated that the adolescents did not report high prevalence
of oral conditions. The OHIP was associated with perceived treatment need, reporting
of dental caries and increased DMF-S index. These results suggest that the OHIP
has good psychometric properties when applied to children and could be a promising
instrument for screening priority care groups.

Indicators
associating oral conditions to individuals' quality of life have been developed
because of the need of understanding subjectively perceived health conditions
as well as determining the impact of health conditions on quality of life.6,19
The concept of perceived health need has arisen from the health promotion movement
started in 1974, when the notion of health was dissociated from absence of disease.
Health and disease have been then considered two distinct multidimensional entities
and thus not measurable in a linear unidimensional scale. Health has been defined
as a quality of life component.10

Among several
instruments that have been developed to measure perceived needs, the Oral Health
Impact Profile (OHIP) is most widely used in studies of people with different
cultural background and sociodemographic profile. The OHIP was developed to
provide a wide measurement of dysfunction, discomfort, and disability related
to oral conditions. This information adds up to conventional indicators of oral
epidemiology of clinical diseases providing thus a profile of "disease impact"
on people and the effectiveness of health services in reducing these impacts.
Originally, the OHIP comprises seven components and 49 items arranged in a questionnaire
format and a 5-choice Lickert-like scale ranging from never to often is used
in the answers. Data consolidation can be performed using a discrete scale or
by scoring each scale interval from 0 to 4.18

Traditionally,
perceived need indicators have been designed for adults and elderly. Still,
Broder et al4 (2000) have conducted a study among urban teenagers
of New Jersey, US, aged 12 to 14 years, comparing an objective indicator, DMF-T
index (index comprising the sum of decayed, missed and filled teeth) and two
subjective indicators (RAND-36-Item Health survey which measures general health
similarly to the OHIP and comprises eight health concepts  physical health
problems, role limitations caused by emotional or mental problems, energy/fatigue,
emotional well-being, social functioning, pain, and general health perceptions
 and the OHIP-49). The authors noted that subjective indicators, OHIP in particular,
could be a valuable sensitive screening instrument for identifying those people
in a community under high impact of oral health conditions.

The OHIP
has been designed in English for a particular cultural background. Hence, for
adapting the indicator into Portuguese and the Brazilian cultural background,
Almeida et al1 (2001) carried out a two-step cross-cultural translation.
In the first step, the semantic validation of the cross-culturally translated
instrument was carried out piloting it among users of the Brazilian Unified
Health System's (SUS) health clinics from different age groups. In the second
step, the instrument's psychometric properties were tested in samples of adult
and elder populations.

Since OHIP
semantic and psychometric validation had been carried out only in adult and
elder populations and had not been before assessed in children and adolescents,
this study aimed at evaluating OHIP psychometric properties in young people.

METHODS

Secondary
data from an epidemiological survey conducted by the Sabará's Health
Department in 20011 was used.
The survey data had been collected through an informed decision process, researchers
had contacted all participants' parents who authorized their children to be
interviewed and the confidential report of findings. The utilization of the
present study data has been previously authorized by the municipality's Dentistry
Division and consisted of reports of oral caries examinations as well as questionnaires
on perceived need (OHIP-14) applied to 312 public school boys and girls aged
12 years old from seven different areas. Other OHIP studies found variation
coefficients (d/µ) ranging between 0.63 and
2.46 for dentate people and between 1.00 and 3.46 for edentulous people. In
order to detect a 15% difference in mean scores for a category with a variation
coefficient of 1.0, it was estimated that 251 people would be necessary for
a type I error equal to 0.05 and a type II error equal to 0.20.

A simplified
OHIP-14 questionnaire comprising 14 items was used as a measurement instrument.
OHIP reliability was assessed using Cronbach's alpha coefficient and intraclass
correlation coefficient (ICC). The ICC was used as an estimate of the total
variability given by the sum of the natural variability and the measurement
error variability.

Content
validity was evaluated through two global scores: perception of treatment need
and perception of dental caries. The correlation of OHIP with the global scores
was assessed through Pearson's linear correlation. Univariate logistic regression
analysis was applied to determine the association between the global scores,
considered independent variables, and OHIP components.

To evaluate
the construct's validity the sample was grouped according to the three categories
of the DMF-S index (measuring the sum of decayed, missing, and filled surfaces):
0 to 5, 6 to 10, and above 10. DMF-S 0 to 5 was set as reference for allowing
the comparing of the two other categories. A mean OHIP-14 was obtained for each
one of the three groups. Means were then compared using Student's t-test for
non-paired samples. Non-paired Student's t-test was applied to test the null
hypothesis that OHIP means of the studied groups were equal.2,3 The
Tukey-Kramer test was also used for different size groups for allowing multiple
comparisons (simultaneous inferences), particularly for all comparisons among
DMF-S groups.

The study
sample consisted mostly of females (160; 51.3%). When evaluated for a global
subjective score, most (171; 55.5%) reported they needed oral treatment. Regarding
their perception of dental caries, when asked, "do you think you have any cavities?",
almost half were positive (124; 46.1%). This outcome had a high concordance
with the occurrence of dental caries measured by both the DMF-S (45.2%) and
DMF-T (41.01%) indexes.

The results
of Cronbach's alpha coefficient were considered low ranging from 0.55 to 0.26.
For all components together, a significant value of 0.8575 was found. Overall,
ICC was similar to Cronbach's alpha.

The Pearson's
test between OHIP components and reported perception of oral treatment revealed
a positive though weak correction, ranging between 0.156 and 0.278. The difference
between mean scores of each OHIP subscale, divided into those subjects reporting
they needed treatment and those reporting did not need treatment, was significant
only for the components pain, psychological discomfort, and psychological disability.
The odds ratio ranged between 1.208 and 1.564, i.e., subjects who reported pain
in the OHIP were about 1.5 times more likely to report treatment need when compared
to subjects who did not report pain in the OHIP.

Data relating
to each component were disposed into 2x2 tables where the lines show the two
classifications of predictive variables, perception of treatment need and perception
of having cavities and OHIP components. As the classifications were independent,
odds ratio was calculated using the following equation:

OR = (a*d)
/ (b*c)

Odds ratio
yielded point and interval values indicating the likelihood of a group of experiencing
impacts when compared to other group (perception of treatment need and perception
of having dental caries).

Table
3 shows the correlation and univariate regression analysis between each
of the seven OHIP components and all of them together and reporting dental caries.
The Pearson's linear correlation linear between OHIP components and the reported
perception of dental caries showed a positive though weak correlation.

The difference
between mean scores for each OHIP subscale, divided into those subjects reporting
having dental caries and those reporting not having caries was significant for
all components, except for deficit (p<0.06). The odds ratio ranged between
1.113 and 1.549. There were recorded two global perceptions regarding the subjects'
oral health: need of oral treatment and perception of dental caries.

Table
4 exhibits the results of OHIP components according to the three DMF-S cut-off
values: 0 to 5; 6 to 10, and above 10.

The comparison
table among different mean OHIP scores according to DMF-S categories using ANOVA
showed a significant difference for the components social disability and deficit.

The contrasts
among DMF-S categories, arranged as dummy variables, indicated that, for the
component social disability, the variable DMF-S 0 to 5 showed to be significantly
different when compared to variable DMF-S above 10. For the component deficit,
the variable DMF-S 0 to 5 had a significant difference when compared to the
variable DMF-S above 10. All other comparisons were not significant.

DISCUSSION

The study
sample consisted of 312 children aged 12 years from public schools in the municipality
of Sabará, Brazil. The original study2
with an active search had a high global response rate that varied per item studied.
Regarding length of residency, missed answers were only 4.0% while for perception
of treatment need 26.0% were either "do not know" or not answered. There was
a higher response compared to 75% response rate reported for a questionnaire
sent by mail by Slade et al13 (1995), 57.6% by Hunt et al7
(1995), and 74.4% by Slade et al15 (1996). These authors also noted
that after reviewing several studies they found a response rate between 71%
and 86% for the OHIP sent by mail. The average response rate was better than
86.8% reported by Miotto & Barcellos11 (2001), and similar to
94.92% by Silva12 (2001), both adopting the same search strategy
as the present study.

OHIP-14
reliability was assessed through the internal consistency method of coefficient
correlation using Cronbach's alpha coefficient. The measured reliability was
low to moderate. Similar intraclass correlation coefficients (ICC) were obtained
though they were systematically lower when compared to Cronbach's alpha coefficients.
These results were lower to those previously reported by Slade & Spencer16
(1994) who obtained Cronbach's alpha coefficients ranging between 0.70 and 0.83
for six subscales and similar to 0.37 obtained in the deficit subscale. The
present study showed lower results than those previously reported by Slade &
Spencer17 (1994) that were between 0.42 and 0.77 for six subscales,
and higher than 0.08 for social disability. These findings are lower than those
reported by Locker & Slade9 (1993) who found values ranging between
0.80 and 0.90 for all components. They are also lower than 0.96 Cronbach's alpha
coefficient obtained by Slade et al15 (1996) and 0.88 obtained by
Slade19 (1997). Silva12 (2001) described an internal consistency
measured using Cronbach's alpha coefficient ranging between 0.6138 for psychological
disability and 0.7720 for psychological discomfort assessed using the simple
intraclass correlation coefficient. The obtained values ranged from 0.4427 for
psychological disability to 0.6292 for psychological discomfort.

Some of
the following factors could have contributed to the study results: method used,
cross-cultural translation, fewer items in the questionnaire, and respondents'
various schooling. Slade et al13 (1995) reported that when a standard
interview was applied instead of a questionnaire sent by mail, OHIP-49 showed
a lower internal consistency. Slade19 (1997) noted that in studies
where the OHIP had been translated into other languages such as French and Spanish,
some questions and categories could not be properly translated and thus affecting
the instrument's reliability. In the OHIP-14's cross-cultural translation process,
difficulties were reported concerning the translation of some terms into Portuguese.1
Shortening the number of OHIP-49 items which gave rise to the OHIP-14 could
have contributed to the instrument's lower reliability. In the OHIP-14 study,
most result comparisons were carried out using the complete instrument. A general
psychometry principle states that "the lower the number of items the lower the
scale consistency". The OHIP-14 has a third less items than the original instrument,
which could explain the low reliability seen in the present study.

Aiming at
assessing whether there were potential redundancies in the questionnaire, internal
correlations of OHIP items for each component were conducted. The Kendall's
correlation showed concordance among the items, i.e., the OHIP-14 items captured
different aspects including the contents of each component.

The Pearson's
test between OHIP components and reported perception of oral treatment yielded
a positive though very weak correlation. However, the difference between mean
scores of each OHIP subscale, divided into subjects who reported treatment need
and those reporting dental caries, was statistically significant for pain, psychological
discomfort, and psychological disability. The odds ratio showed that subjects
who reported pain in the OHIP were about 1.5 times more likely to report treatment
need when compared to those who did not report pain. This finding suggests the
good validity of OHIP's contents concerning the global indicator of reported
perception of oral treatment need.

In the analysis
of predictability using a logistic model, the likelihood of a subject to report
pain as well as oral treatment need was high, suggesting a good validity of
OHIP's content to predict the need for oral treatment. This finding shows that
the OHIP has a good predictive value for reporting oral treatment need and the
component pain had the highest predictive value.

The correlation
analysis between OHIP components and the reported perception of dental caries
also showed a positive though weak correlation. Despite that, the difference
between mean scores and odds ratios of each OHIP subscale, divided into subjects
who reported having dental caries and those who reported not having caries,
was significant for all components.

The predictive
logistic model applied to determine the effect of reporting in an OHIP component
as well as reporting dental caries was moderate to low, indicating a moderate
content validity of OHIP to predict the reported dental caries. These results
indicate that, as expected for this age group, while reported pain had the highest
predictive value of perception of dental caries, the predictive value of a positive
reporting in the OHIP was only moderate for perceived caries.

To assess
validity properties of the OHIP's construct the DMF-S index was divided into
three categories: 0 to 5; 6 to 10; above 10. The comparison between different
mean OHIP scores, according to the DMF-S categories and using ANOVA, showed
a significant difference concerning social disability and deficit. In order
to determine the categories in which differences were seen, the Tukey's test
was used and a significant difference was found only in the ends of DMF-S for
social disability and deficit. These results are similar to those reported by
Slade & Spencer17 (1994), who found high impact in patients showing
high values in objective indicators. They also corroborate what found Coates
et al5 (1996) that HIV-positive patients who had many oral conditions
reported a significant high impact. Moreover, they confirm the findings of Slade
et al14 (1997) that oral conditions such as missing teeth, retained
root fragments, and periodontal pockets among others were associated with high
impact. It also partially corroborates Locker & Jokovic8 (1996)
study when no significant association between subjective and objective indicators
was found. Also, it agrees with Slade's19 (1997) research showing
that higher OHIP scores were seen in individuals with less favorable oral-medical
conditions (more missing teeth, more root fragments, more untreated caries,
deeper periodontal pockets, and more periodontal recesses).

The statistical
significance verified only in three components contrasts with the results reported
by Broder et al4 (2000), who found a significant difference for all
OHIP components while evaluating adolescents. Most probably this difference
could be due the different epidemiological profile of the studied groups in
Sabará and New Jersey. While in Sabará the mean DMF-S was 2.24
and 54.8% of the sample had DMF-S zero, in New Jersey the mean DMF-S was 8.8
and only 5% of the sample was DMF-S zero. As the frequency of individuals with
DMF-S above 10 was very low in the present study, the statistical power of the
sample was affected for rejecting the null hypothesis in some components. Overall,
the frequencies found in the OHIP were much lower than those reported in other
studies, including among adolescents.

The study
results indicate that the prevalence of perceived dysfunction, discomfort and
disability as an impact resulting of oral health conditions in children aged
12 years in Sabará, measured using the OHIP-14 instrument, was very low.
The study results allow for reaching the conclusion that the OHIP instrument
has good content validity for selecting groups of patients who perceive treatment
need and only moderate validity for identifying patients reporting dental caries.
The OHIP-14 has good criteria validity for the components social disability,
deficit, and psychological disability when comparing the association of the
instrument's scores with DMF-S index.